The Replay Processor should avoid reparsing replays

[jordan-zilch]

I'll often hit dpad down to mark a replay when I want to clip something, so that I can come back to it later with Clippi. Like most Slippi users I have a single folder with thousands of replay files, and every time I want to look for new clips, Clippi reprocesses all of these replays. Parsing my whole replay folder takes something like an hour. It takes significantly less time if I move not-yet-processed files into another folder and point Clippi to the new folder instead. However it's not easy to remember which clips were and weren't processed, and then you also have to move your replays back at the end if you like to keep them all in one place. Overall I think this workflow could be smoother.

Clippi should keep track of files that were previously processed with a given set of search settings, and avoid reprocessing them. This could be achieved by adding additional information (the search settings, filenames or hashes of already-processed replays) to the output file, and allowing Clippi to take in a previous output file as input to update it with new replays.